Thursday, November 8, 2012

The interplay between science and objectives in fisheries management

The blogosphere this week will no doubt be dominated by discussions of the U.S. election. I spent the week far away in Santa Marta, Colombia, attending the 65th Annual Meeting of the Gulf and Caribbean Fisheries Institute. Two topics have dominated the presentations, posters, and discussions here: invasive lionfish, and how to manage poorly-studied fisheries.

Lionfish are pretty to look at and apparently good eating if you can catch and clean them without getting stabbed by their large poisonous spines. I can personally vouch for how easy it is to spear them. On a fishing expedition this summer, I managed to catch three, while other reef fish leisurely swam away from me, confident I couldn’t hit the broad side of a grouper. The problem is that lionfish are invaders. They were first recorded living wild outside of their native Pacific Ocean in 1985, from a sighting in Florida. They presumably were introduced by aquarium owners who didn’t have an adequate tank for a growing and voracious predator that likes to eat small fish, no doubt including its tank-mates. Since then, lionfish have become a major part of coral reef ecosystems across the Caribbean, and may be depleting their prey fish while also slowing the recovery of fellow predators. Efforts are underway to promote lionfish fisheries, in the hope of controlling them. We know little about this potential fishery, but we at least have a clear idea of what we want out of it—to reduce the numbers of lionfish.

By contrast, most poorly studied fisheries present two problems: we do not understand their ecology well, and people have different ideas about what they want from the fisheries and the ecosystems that support them. Even in parts of the world with wealthy governments capable of performing state-of-the-art studies, most marine fisheries are poorly studied. The U.S. government, for example, manages and is required to report status annually1 of 498 fish stocks spanning waters from Alaska to the U.S. Virgin Islands. Government scientists have only identified the health of 40% of these stocks. In the tropics, the situation is worse: only 25% of U.S. Caribbean stocks and less than 20% of Hawaiian/Western Pacific stocks have been assessed. Although the U.S. now has rules that require the specification of annual catch limits for all species, there is a strong tradition of paying inadequate attention to poorly studied stocks, using their unknown status as justification. In providing more attention, we are faced with the question of what we want out of the fishery and ecosystem.

We struggle with this issue in all fisheries, but the choices are especially stark when we have little information to guide us. Ironically, this lack of guidance may be the key to future success, because it makes it hard to ignore the interplay between objectives and science. The reality is that we can manage a fishery with very little data, setting objectives for current and future catches. The hitch is that we may not be able to sustain these catches, so we need a mechanism to adjust when some simple data collection program tells us the stock is in decline. The need for responsive catch limits was a key lesson from my foray into rocket science. The rules by which we make adjustments will shape the benefits we get from this system, including the catch levels, variability of catches from year to year, and the likelihood of avoiding a stock collapse that would necessitate low catches to allow for rebuilding. Informed fishermen, managers, and the public can negotiate over these benefits to craft a minimal data management system and then adapt it over time as we learn more about the fish stock. There is a general movement towards systems of this sort that prescribe catch limits as a function of data on the abundance of the stock, but mostly for better-studied stocks. Even in these cases, decisions about the systems are often made without a clear understanding of the trade-offs in objectives inherent in the decision. In order to manage data-poor stocks, we must use systems of this sort. In doing so, we can highlight how to do a better job for all fisheries.

Tomorrow, I present my work on Colombia’s Caribbean spiny lobster fishery. In recent years, economic conditions have kept fishing effort down and the stock appears to be quite healthy. Economic conditions are improving, though, and there are a lot of lobsters to be caught, so the healthy status is most likely temporary. I am spending next week reviewing the data on finfish (as opposed to shellfish) fisheries in the same region. I already know the data are extremely poor, and hope that reviewing management options with the Colombians will underscore the value of a minimal data management system that includes automatic adjustments to the annual catch limits. Hopefully, by going through this exercise in a case where data are so limited, I will successfully illustrate the benefits of crafting a similar policy for the better-studied lobster fishery. I will keep you posted.

Best regards,

1 39 fish stocks are excluded from this requirement, most of which are salmon and many of which are endangered or threatened.

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